, Dated

Press Release, Dated July 31, 2017

Geron Announces Updates to Imetelstat

Clinical Development

Conference Call Scheduled for 8:00

a.m. ET on Tuesday, August 1

MENLO PARK, Calif., July 31, 2017

-- Geron Corporation (Nasdaq: GERN) today

announced updates to the clinical development plans for IMerge and IMbark, the

ongoing trials of the telomerase inhibitor imetelstat in lower risk

myelodysplastic syndromes (MDS) and relapsed or refractory myelofibrosis (MF),

respectively, being conducted by Janssen Research & Development, LLC. For

IMerge, Part 1 will be expanded to enroll additional patients in a refined MDS

population to confirm the clinical benefit and safety observed from current

results. For IMbark, the trial remains unchanged. Geron expects that the IMbark

protocol-specified primary analysis, the completion of which triggers a future

Continuation Decision by Janssen, will begin no later than the third quarter of

Original Trial Design

IMerge (NCT02598661) is a Phase 2/3

clinical trial evaluating imetelstat in transfusion dependent patients with Low

or Intermediate-1 risk MDS who have relapsed after or are refractory to prior

treatment with an erythropoiesis stimulating agent (ESA). The clinical trial is

in two parts: Part 1 is a Phase 2, open-label, single-arm design in

approximately 30 patients and Part 2 is designed to be a Phase 3, randomized,

controlled trial in approximately 170 patients. The primary efficacy endpoint is

the rate of red blood cell (RBC) transfusion independence (TI) lasting at least

In Part 1 of IMerge, 32 patients were

enrolled, of which a subset of 13 patients had not received prior treatment with

either a hypomethylating agent (HMA) or lenalidomide and did not have a del(5q)

chromosomal abnormality. As of May 2017, the 13-patient subset showed an

increased durability and rate of transfusion independence compared to the

overall trial population ( 8-week RBC-TI: 53.8% vs 34.4%). The safety profile

in Part 1 was consistent with prior clinical trials of imetelstat in hematologic

malignancies, and no new safety signals were identified. The most common adverse

events were cytopenias, which were manageable, and included grade 3/4

neutropenia and thrombocytopenia.

Based on these data from the 13-patient

subset, the Joint Steering Committee has decided to amend Part 1 of the protocol

to enroll approximately 20 additional patients who are non-del5q and na ve to

HMA and lenalidomide treatment in order to increase the experience and confirm

the benefit-risk profile of imetelstat dosed at 7.5 mg/kg every four weeks in

this refined target patient population. Enrollment into the expanded Part 1 is

expected to begin in the fourth quarter of 2017.

Separately, a data package and proposed

refinements to the trial design for Part 2 of IMerge were previously provided to

the FDA following an internal data review completed by Janssen in April, and

related interactions are ongoing. Feedback from ongoing FDA interactions, data

from the expanded Part 1, and other imetelstat program information, including

the protocol-specified primary analysis for IMbark, are expected to inform

Janssen s decision of whether to move forward to Part 2 of IMerge.

Detailed results for the original 32 patients in Part 1 of IMerge, including key secondary endpoints of hematologic improvement and rate

of RBC-TI lasting at least 24 weeks, as well as duration of response and

detailed safety information, will be submitted for presentation at a major

IMbark (NCT02426086) is a Phase 2 trial in

patients with Intermediate-2 or High Risk MF who have relapsed after or are

refractory to prior treatment with a JAK inhibitor. The trial continues without

modification, and patients remaining in the treatment phase may continue to

receive imetelstat. All safety and efficacy assessments will be conducted as

planned in the protocol, which includes an assessment of a potential survival

benefit associated with imetelstat treatment. To date, median overall survival

has not yet been reached in either the 4.7 mg/kg

or 9.4 mg/kg dosing arm. Enrollment of new patients to the trial remains

suspended because the total number of patients enrolled to date is adequate to

perform the protocol-specified primary analysis. Geron expects Janssen to

perform an internal data review in the first quarter of 2018 to enable a

potential protocol amendment to allow the long-term treatment and follow-up of

patients, including for survival, beyond the current April 2018 per-protocol

Continuation Decision

The Joint Steering Committee has agreed

that the timing of the protocol-specified primary analysis for IMbark will begin

upon the earlier of either a pre-specified number of deaths occurring in the

trial or the end of the third quarter of 2018. Following completion of this

primary analysis, which includes an assessment of potential survival benefit

associated with imetelstat treatment, Janssen will notify Geron whether it

elects to maintain the license rights and continue the development of imetelstat

in any indication, i.e., the Continuation Decision.

At 8:00 a.m. EDT on August 1, 2017,

Geron s management will host a conference call to discuss these updates to

imetelstat clinical development. Participants can access the conference call

live via telephone by dialing 877-303-9139 (U.S.); +1-760-536-5195

(international). The conference ID number is 42220500. A live audio-only webcast

is also available through the company s website at www.geron.com in the

Investors section under Events and at http://edge.media-server.com/m/p/oqg6hyn5.

The audio webcast of the conference call will be available for replay

approximately one hour following the live broadcast through September 1,

Imetelstat (GRN163L; JNJ-63935937) is a

potent and specific inhibitor of telomerase that is administered by intravenous

infusion. This first-in-class compound, discovered by Geron, is a specially

designed and modified short oligonucleotide, which targets and binds directly

with high affinity to the active site of telomerase. Preliminary clinical data

suggest imetelstat has disease-modifying activity by inhibiting the progenitor

cells of the malignant clones associated with hematologic malignancies in a

relatively select manner. Most commonly reported adverse events in imetelstat

clinical studies include fatigue, gastrointestinal symptoms and cytopenias.

Imetelstat has not been approved for marketing by any regulatory authority.

About the Collaboration with Janssen

On November 13, 2014, Geron entered into

an exclusive worldwide license and collaboration agreement with Janssen Biotech,

Inc., to develop and commercialize imetelstat for oncology, including

hematologic myeloid malignancies, and all other human therapeutics uses. Under

the terms of the agreement, Geron received an upfront payment of $35 million and